This invention relates to a method for identifying optical disks, the manufacture of cartridge-enclosed optical disks, and optical disk-enclosing cartridges.
A variety of optical read only disks, optical recording disks, and magnetooptical recording disks have been developed and utilized as various document and image storage files. These optical disks should be accommodated in casings or cartridges in order to keep off dust, Some manufacturers recently proposed to use optical disks as accommodated in a standardized cartridge similar to that of floppy magnetic disks. As is well known in the art, the standard for cartridges of magnetic floppy disks, for example, 31/2 inch disks defines the provision of a so-called called write protect tab window at the predetermined corner of the cartridge.
FIG. 18 illustrates a fragmental portion of a standard prior art cartridge with a write protect tab. The cartridge generally designated at 1 includes an upper shell 11 with a first aperture 21 and a lower shell 15 with a second aperture 25. The second aperture 25 is larger than the first aperture 21 and is disposed in registry with the first aperture in a direction perpendicular to the upper and lower shells 11 and 15. The first and second apertures 21 and 25 together define a through hole 3, the through hole 3 serving as a write protect window. The lower shell 15 is provided with a tab 40 for sliding motion over the area of second aperture 25 in a direction indicated by double-sided arrow a.
The tab 40 is illustrated at the position where the tab does not shield the overlapped area of the through hole 3 between the first and second apertures 21 and 25, presenting a protected or unrecordable state. If the tab 40 is moved upward (inside) from the illustrated position, the tab shields the overlapped area of the through hole 3 between the first and second apertures 21 and 25, presenting a recordable state. Whether or not the tab 40 shields the overlapped area of the through hole 3 between the first and second apertures 21 and 25 may be detected by means of a sensor switch in the form of a mechanical switch which is provided in the drive system though not shown in the figure. The sensor switch can be inserted into the through hole 3 in the direction indicated by arrow b. Then the sensor switch detects two states, unrecordable and recordable states in terms of the extent to which the sensor switch can enter the through hole 3.
It was proposed to establish a standard for cartridge-enclosed optical disks by prescribing such a write protect tab.
At present, optical disks are available in various standards and types. If disks of different standards can be operated with a single drive system, it is convenient for the users. Efforts have been made to provide such compatibility. In order that a single drive system operate optical disks of different standards and types, the drive system has to identify the standard or type of a particular disk.
If the write protect tab illustrated in conjunction with the conventional floppy disk cartridge is applied to the optical disk cartridge, it becomes possible to identify two bits of information. Identification of only two types of information is unsatisfactory for optical disks. The cartridge must be further provided with a newly standardized aperture or recess before an additional set of information can be applied to the optical disk.